Taking Subaru out of AWD with fuse added

Asked by Jan 26, 2016 at 07:48 AM about the Subaru Outback

Question type: Maintenance & Repair

I just purchased a 97 Outback AWD. It was shaking at low speeds at turning.
Brought to a mechanic and he mentioned the fuse thing. He put a fuse in the
FWD slot under the hood. The shaking went away. What is really the problem?
How long should I drive like this? I'm in New England, I could use AWD.

18 Answers


Was the original fuse blown? Or did he just put one in due to being taken out by some other person? Do you know the exact fuse location and number or size?


He changed a fuse out or removed the fuse?

There was not a fuse in there. Not sure of the voltage. Is there a problem with the coupler? It sounded like it would cost a lot to fix but he didn't actually say how much. He said something to the fact that uneven tread on tires could have caused it or just wear on the car. I was helping a family member by buying from them. I have 4 new tires and front alignment done, don't you think they would of felt the shuffle when the turn the wheel at 10 mph? I would like to use awd but not sure if I will be able too if it's gonna cost too much to fix


The "chatter" you're experiencing is due to lost lubricity in the AWD transfer case bushings. Read carefully: 1. the empty fuse slot is just a convenient place to stick in any fuse (or paper clip, etc) to short out the RWD transfer case part of the AWD transmission. In effect the rear driveshaft now turns randomly, not providing any linked torque to the rear differential. Its convenient inclusion was strictly to allow towing Subarus while dragging the rear end by a non-flatbed truck. By shorting out the system you are removing the source of the "chatter", as it is called. 2. This "chatter" is caused by worn teflon bushings in the transfer case of the AWD. In a newer valuable Subaru the remedy is to replace said "box" with a used one. We used to do this for about $600...cheaper than swapping in a whole used autobox ($1500). 3. Since your aged-out OB is probably not worth this financial hit, try the "emergency" fix that works surprisingly well: first, drain and refill the AT with 3.5 qts new ATF. Drive for a day or two. Regardless of whether the chatter subsides, REPEAT! (this isn't shampoo...you have to try to get MOST of the accumulated dirt out before the following reconditioning). 4. Is the chatter now all gone? 5A. NO: add either a small bottle of GM's Positive Traction rear differential additive OR a bottle of TransX Posi-Trac (which I prefer) to the filled AT. Drive in figure-8's or donuts for a few minutes then normally. Seemingly magically the chatter will disappear! (Note that my cheap Mainiacs up north use a jigger glass (1.5oz) of brake fluid instead, but that can wreak havoc with the AT's internal rubber seals, making the AT not rebuildable in the future. But who cares?) 5B YES: you're done. You've dodged a bullet. 6. Continue to drain ONCE and refill AT (again 3.5 qts Dexron) annually as preventative maintenance. We've saved many hundreds (thousands?) of AWD AT's this way...usually the "repair" is durable. You've probably dodged a bullet; now just try to find a bottle of Trans-X Posi-Trac and 7 qts ATF and get to work...and don't forget to toss that fuse!

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Wow. Where do I get the best fluids? Auto Zone, CAP, etc. Okay, so get the fluids, Drain, Add, take the fuse out, drive. (chatter goes away)done. If not, add GM's positive traction additive/or TransX to AT fluid, drive in circles. Then the car is AWD again. So, is it easy to drain the fluid? Size wrenches?I don't have a garage to use presently so I have to do it outside. Is temperature a factor? I appreciate all the information you have giving me. The car is from California, no rust, only 134000. New brakes, tires, battery,alternator, etc. Never had AWD, would like to try it with NE weather. :)


Any "normal" (not Ford or old Honda) ATF is fine. Again, I'd perform TWO drain/refills before removing fuse; drive a half hour between and after just to mix well. THEN remove fuse to try AWD. At this age I'd add the TransX anyway as it never seemed to hurt anything. Only $12 if you can find it. Access is underneath from the LEFT side, but the 17mm drain bolt is pretty close to the trannie's centerline, so BE CAREFUL to use TWO left side jacks, raising high enough so you can slide your body halfway under there and apply enough leverage to untighten the bolt. 3.5qts of ATF will splash down into your catchbin. Let it drain for two minutes or more. Reattach plug. Open hood, look for yellow-tipped (maybe black back in '97) dipstick lower down under the driver's side windshield. Make /use a funnel long enough and small enough at the tip to refill the AT w/ 3.5qts. (Ignore what the dipstick reads.) If the drained ATF is mysteriously already clean (pink) then somebody changed it recently, so just add the Trans-X as the chatter isn't due to dirty fluid byt worn bushings. But if the ATF looks brown-black rather than clear pinkie-gray please do it TWICE. The reason is that the 4EAT holds 8.8qts (!), and you're only draining 40% each time. So at least with TWO efforts you're removing (0.4x8.8) + 0.6(0.4x8.8) = 64% of the total dirt. IMPORTANT NOTE: Garages that've bought electronic "power flush" pumps for AT service will try to sell you a "complete flush" for $90-100. ABSOLUTELY DO NOT EVER power flush a Subie tranny as the BACKWARDS flow of the solvent will remove deposits and send them up into the sensitive valves and throttle body, destroying function. So just let it poop out...maybe twice...but NO ENEMAS! Good luck. If you don't retrieve a completely "clean" chatterless drive then try to avoid locked turns, such as when parallel parking. Some folks add a fuse for three season driving to lower stress on a worn transfer case, removing it in winter...or after it snows or gets icy. Another rationale was that this forced FWD mod saved gas, but since the driveshaft spins anyway, the diff is less than 1mpg, and Subie corporate used to warn that such use could destroy the transfer case, driveshaft, and/or rear differential. I don't have a large enough sample of consequent failures to draw reliable conclusion. (Harbor Freight has a nifty aluminum on-sale $60 lift that I use often. A pair of these is a good investment. The much smaller ones simply aren't strong enough nor raise the chassis high enough for easy access to the ATF drain plug.) Good luck...you will probably be successful...it it's not too late. Ern


Poor the WARMED ATF slowly into the funnel as that funnel you're using has a small hole, eh? Be patient...it'll be worth it if you save your trans.


Oy: "poor" < "pour"

Its going to warm this weekend. I'll go get the fluids! I will keep you posted. Thanks again.

Okay, bought supplies. Drained the AT fluid. "Black/yuck". Pour 3.5 more in. Going to drive it. Now you mention Trans-X Posi-trac. Question. On the tube it said not to add to AT Fluid? Did I not get the right one? Did some more reading, what about "Lucas Oil Transmisson Fix" that does say add to AF fluid. Changed oil while under. Going back to Walmart to return dirty oil. Then back to do it again......let me know about the Trans-X?or Lucas? Thanks


Drive the tranny for an hour or so to mix well. Then drain again (since it was black). Does the second draining seem cleaner? Hope so. Then add the Trans-X (ignore the label caveat), and drive a few minutes. The chatter should disappear. UNDER NO CIRCUMSTANCES THICKEN THE ATF WITH LUCAS MOLASSES! It WILL make it worse! Your aim here is to clean and increase the lubricity of the fluid...NOT thicken it up! LUCAS has NEVER helped a Subie autobox...and has hurt many. Just do what I said and report back before I fly to Asia Wed night. Ern

Well.....we drained it again, much better color. Hesitated about Trans-X.....added Lucas, drove around in circles. Slow stops, and turns. Took fuse out. Drove more circles, highway. So far felt better. Will drive again tomorrow. Are you suggesting, I drain again since I used Lucas?? I still have the Trans-X (tube not can), can was not Posi-trac. What type of reaction do you expect to happen with Lucas. Should I give it a chance? Or is the damage done.


Ok, but fix this error! You have temporary improvement because of the new 40% ATF, NOT the friggin' Lucas! The now-Lucas'ed ATF mix will soon get dirty again, and being thicker, will chatter SOONER! So drain this mess, add another 3.5 qts ATF, and the tube of TransX Posi-Trac. It WILL work to reduce chatter to probably nil longterm. Wish you had followed my advice initially. Sheesh....

The car is driving fine. My question is why would you have me put a product in the car that the manufacturer says not too? I just got off the phone with Trans-X CS and they said the right product should be the can with the Slip and Leak #402015. It seems you know a lot about Subaru's but it the directions on the manufacturer's website said not to use( Posi-trac), I had to question it. What is wrong with the "can" product that they make. I'm not a mechanic but I watch, listen and read. The manufacturer would not agree to what you wanted me to do. Thank you for making me change the fluid, it needed it badly. Have a nice trip to Asia.


nailteck. You raise a good question. I await others answers. Even Lucas is a question but a well worn diff is different than a new one within all the proper specs for clearances.

So, I changed the Automatic Transmission Fluid that was needed badly. The car shuffling while turning at low speeds has subsided. With the fuse out as well. I have not done anything with the differential component. As far Lucas vs Trans-X, would the shuffling(chatter) had gone with just the ATF? The car has 134,000 miles on it. I couldn't tell you if the ATF was ever changed, same as differential components. I appreciate all the advice and instructions. When the tube of the Trans-X said not to use in automation transmission, I didn't, even though it was suggested. If the chatter comes back, could it still be the differential? Could it be that the Lucas didn't do enough? Should I have put in the other Trans-x product that the company suggests? Not the Posi? I guess we'll see. I'm looking forward to driving a AWD in new england with our crazy "winter" that we are having. Who know it we'll ever get snow like last year! Thanks


Do I have to repeat myself AGAIN?! The Lucas will NOT help lubricate the worn transfer case bearing seats in the AWD. The Trans-X Posi-Trac WILL. This is a special purpose app...ignore what your read on the damned bottle. YES, the partially cleaned fluid reduced the chatter, but maybe only temporarily. The Trans-X "tube" stuff will help reduce the continuing wear on the worn parts dramatically. If you start to feel even light chatter again you'd better redrain the ATF (because the chatter has stressed the clutches again, dirtying the ATF once more), and get that Posi-Trac in there. Eventually NOTHING will help and you'll have to chase a new transfer case or whole used autobox. That you somehow think you can outsmart this well- honed traditional repair that's worked for many thousands of old Subies by using Lucas molasses is both baffling and frustrating. Sigh....


TheSubaruGuruBoston One question: Have you seen the Lucas demo: clear plastic enclosed frame with a crank and gears. The one with Lucas definitely has more lubrication sticking to the gears versus the other standard oil model. What do you think of it? Seems convincing to me to be helpful where gears are worn beyond original specs?

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